Semiconductor array imager for printing systems
A laser imager for a printing system, comprising a plurality of independently addressable surface emitting lasers arranged in a linear array on a common substrate chip and including a common cathode and a dedicated control channel associated with an address trace line for each laser of the plurality of independently addressable surface emitting lasers, and optical elements arranged in a linear lens array configured to capture and focus light from the plurality of independently addressable surface emitting lasers onto a imaging member, wherein the plurality of independently addressable surface emitting lasers arranged in a linear array and the optical elements arranged in a linear lens array operate together to image the imaging member.
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Embodiments are related to semiconductors laser arrays. Embodiments are also related to semiconductor imager arrays for use in printing systems. More particularly, embodiments are related to providing independently-addressable vertical cavity surface surface-emitting laser (VCSEL) architectures in an imaging array that can produce high power and accommodate tight-pitch packing.BACKGROUND
VCSELs are semiconductor-based lasers that emit light perpendicular to a substrate. If properly designed, technical uses of VCSEL arrays can include data communication systems, light detection and ranging (lidar) systems, printing systems, laser processing systems, zone heating or curing, illumination systems, 3d mapping systems, and facial recognition devices (e.g., smartphone face identification).
High power surface-emitting lasers typically require large apertures because the light-emitting area of the device needs to be big enough to support the requisite high light output. For example, the typical aperture of VCSELs capable of producing 50 mW of light output needs to be about 18 μm in diameter or larger. The overall device size would be larger still because the device structure typically includes oxidation channels and electrical contacts that extend beyond just the aperture.
One of the primary advantages of VCSELs is that if properly arranged they could be patterned into dense arrays with many hundreds or thousands of individual emitters operating as pixels. This would be important because some applications require high power surface-emitting lasers to be packed into tight-pitch arrays, where the linear pitch is comparable to or smaller than the normal dimensions of the device. For example, in 1200 dpi printing applications, where each laser pixel in the array would be used to address one dot on an image, the required linear spacing between laser address lines would be about 21.2 μm. This linear pitch is tighter than the size of current semiconductor laser devices capable of producing 50 mW of light output. Efficient or high intensity semiconductor lasers today often operate in wavelength regions between 550 nm to 1000 nm. The very close spacing between lasers in such arrays can make thermal crosstalk problematic, as heat from each laser can affect the performance of nearby lasers. Also, the aggregate electrical power drop from a large number of high power lasers operating within a small region can lead to a high thermal load density that must be dissipated.
What is needed are independently-addressable VCSEL architectures that can produce high power at a resolution greater than 300 dpi and can accommodate tight-pitch packing while overcoming thermally induced shortcomings.SUMMARY
The following summary is provided to facilitate an understanding of some of the innovative features unique to the disclosed embodiments and is not intended to be a full description. A full appreciation of the various aspects of the embodiments disclosed herein can be gained by taking the entire specification, claims, drawings, and abstract as a whole.
In accordance with the embodiments, a semiconductor laser (e.g., VCSEL) architecture is disclosed that can achieve 300 to at least 1200 DPI digital addressability. The architecture can have features that include improved laser array designs, improved laser array geometries, and chip tiling. In printing applications, for example, VCSELs operating as pixels and deployed in an array format according to the present embodiments can deliver up to and exceeding 50 milliwatts of laser power with aperture sizes that can enable high resolution (e.g., >300 dpi) resolution.
In accordance with the embodiments, a semiconductor laser array can be used as an individually addressable light source in, for example, the DALI (digital architecture for Lithographic Inks) printing process utilizing a dramatically reduced size and complexity for the most sophisticated component in the printing system—the laser imager.
In accordance with the embodiments, a laser imager for a printing system can be provided that includes a plurality of independently addressable surface emitting lasers arranged in a linear array on a common substrate chip and including a common cathode and a dedicated control channel associated with an address trace line for each laser of the plurality of independently addressable surface emitting lasers
In accordance with the embodiments, optical elements can be arranged in a linear lens array configured to capture and focus light from the plurality of independently addressable surface emitting lasers.
In accordance with the embodiments, the plurality of independently addressable surface emitting lasers arranged in a linear array and the optical elements arranged in a linear lens array can operate together to image a blanket cylinder.
In accordance with the embodiments, large area, high power VCSEL arrays as presented herein also can be useful for various applications such as facial recognition, laser sintering, contact-free thermochromic printing, zone heating and curing, and lidar applications.
In accordance with the embodiments, a semiconductor laser array can include a mounting and cooling architecture that can maintain laser operating temperatures and efficiency.
In accordance with a feature of the embodiments, a semiconductor laser array can include direct die attachment to a 3D submount with an integrated cooling channel.
In accordance with another feature of the embodiments, a semiconductor laser array can include a transfer of an VCSEL epi layer onto a metal host substrate.
In accordance with another feature of the embodiments, a semiconductor laser array can implement image frame phase delay addressing.
In accordance with another feature of the embodiments, a semiconductor laser array can use a selfoc lens array.
In accordance with yet another feature of the embodiments, a semiconductor laser array can be integrated onto a 3D submount.
In accordance with another feature of the embodiments, a semiconductor laser array can incorporate a multi-row construction interposer design, including fan-in for ASIC placement tolerance.
The accompanying figures, in which like reference numerals refer to identical or functionally-similar elements throughout the separate views and which are incorporated in and form a part of the specification, further illustrate the present invention and, together with the detailed description of the invention, serve to explain the principles of the embodiments.
The particular values and configurations discussed in these non-limiting examples can be varied and are cited merely to illustrate one or more embodiments and are not intended to limit the scope thereof.
Subject matter will now be described more fully hereinafter with reference to the accompanying drawings, which form a part hereof, and which show, by way of illustration, specific example embodiments. Subject matter may, however, be embodied in a variety of different forms and, therefore, covered or claimed subject matter is intended to be construed as not being limited to any example embodiments set forth herein; example embodiments are provided merely to be illustrative. Likewise, a reasonably broad scope for claimed or covered subject matter is intended. Among other things, for example, subject matter may be embodied as methods, devices, components, or systems. Accordingly, embodiments may, for example, take the form of hardware, software, firmware, or any combination thereof (other than software per se). The following detailed description is, therefore, not intended to be interpreted in a limiting sense.
Throughout the specification and claims, terms may have nuanced meanings suggested or implied in context beyond an explicitly stated meaning. Likewise, phrases such as “in one embodiment” or “in an example embodiment” and variations thereof as utilized herein do not necessarily refer to the same embodiment and the phrase “in another embodiment” or “in another example embodiment” and variations thereof as utilized herein may or may not necessarily refer to a different embodiment. It is intended, for example, that claimed subject matter include combinations of example embodiments in whole or in part.
In general, terminology may be understood, at least in part, from usage in context. For example, terms such as “and,” “or,” or “and/or” as used herein may include a variety of meanings that may depend, at least in part, upon the context in which such terms are used. Typically, “or” if used to associate a list, such as A, B, or C, is intended to mean A, B, and C, here used in the inclusive sense, as well as A, B, or C, here used in the exclusive sense. In addition, the term “one or more” as used herein, depending at least in part upon context, may be used to describe any feature, structure, or characteristic in a singular sense or may be used to describe combinations of features, structures, or characteristics in a plural sense. Similarly, terms such as “a,” “an,” or “the”, again, may be understood to convey a singular usage or to convey a plural usage, depending at least in part upon context. In addition, the term “based on” may be understood as not necessarily intended to convey an exclusive set of factors and may, instead, allow for existence of additional factors not necessarily expressly described, again, depending at least in part on context.
Although specific terms are used in the following description for the sake of clarity, these terms are intended to refer only to the particular structure of the embodiments selected for illustration in the drawings and are not intended to define or limit the scope of the disclosure. In the drawings and the following description below, it is to be understood that like numeric designations refer to components of like function.
Although embodiments are not limited in this regard, the terms “plurality” and “a plurality” as used herein may include, for example, “multiple” or “two or more”. The terms “plurality” or “a plurality” may be used throughout the specification to describe two or more components, devices, elements, units, parameters, or the like. For example, “a plurality of stations” may include two or more stations. The terms “first,” “second,” and the like, herein do not denote any order, quantity, or importance, but rather can be used to distinguish one element from another. The terms “a” and “an” herein may not denote a limitation of quantity, but rather can denote the presence of at least one of the referenced item.
The term “printing device”, “printing system”, or “digital printing system” as used herein can refer to a digital copier or printer, scanner, image printing machine, digital production press, document processing system, image reproduction machine, bookmaking machine, facsimile machine, multi-function machine, or the like and can include several marking engines, feed mechanism, scanning assembly as well as other print media processing units, such as paper feeders, finishers, and the like. The digital printing system can handle sheets, webs, marking materials, and the like. A digital printing system can place marks on any surface, and the like and is any machine that can read marks on input sheets, or any combination of such machines.
The term “pitch” as used herein can refer to the minimum center-to-center distance between interconnect lines. As a half pitch can approximate the minimum linewidth, it can be used as an indicator of an IC's integration level.
The term “semiconductor laser” as used herein can refer to surface emitting semiconductor lasers such as VCSELs (vertical cavity surface emitting lasers) or the like which can be fabricated on semiconductor substrate using semiconductor manufacturing techniques.
When properly designed, current state-of-the-art VCSELs (vertical-cavity-surface-emitting lasers) have the capability of producing enough light output power to be deployed in an array format that, if configured and packaged appropriately, could be used in high resolution evaporation of fountain solutions in high speed printing systems. Such systems require each VCSEL in the array to produce tens of milliwatts of light output power as standalone devices when operated alone and for the VCSEL array and its packaging to be designed so lasers retain that capability even when adjacent devices are simultaneously turned on. Features of embodiments provide, among other things, unique VCSEL array chip designs, that can result in high power small pitch individually addressable lasers, ways to mount, cool, drive, and image large numbers of VCSEL array chips so that wide width (>100 mm) printing can be enabled with the chips, and an example of VCSEL arrays used for printing in the DALI (digital architecture for Lithographic Inks) printing process.
To enable tight-pitch packing of independently-addressable high power surface-emitting lasers on VCSEL array chips described herein. In some embodiments the VCSEL share a cathode and they are individually addressable through individual address lines connecting individual VCSEL anodes. In some embodiments a common anode addressing architecture can be employed where each address line within the array can encompass multiple electrically-connected apertures. Non-symmetric aperture shapes can also be employed that are elongated to fit within the pitch of the address lines. Additionally, the spacing of lasers in the process direction can be tolerated by, for example, the Dali print process to increase the total distance of lasers while still maintaining an effective cross-process spacing that can be smaller than the size of lasers themselves.
“Pixel” can refer to a set of multiple VCSELs or 1 VCSEL. For example, in
The “aggregate linear pitch” as mentioned herein refers the cross process spacing between adjacent cross process direction lasers regardless of their position in the process direction. For example, in
Optimized thermal management of VCSEL array chips can be achieved, with two unique approaches (that can be used together): a) Direct die attach to mechanical blocks that incorporate means of cooling for example by cooling fluid channels or heat pipes, slots for driver chips, and mounting systems for optics and b) Ultra-thin laser epi transferred to thermally-conductive metal host substrates.
Allow stitching of VCSEL array chips is enabled so that the effective (stitched) laser array width meets the demand for today's production print width. The effective laser array contains means to focus the laser light originating from the VCSELs, drive individual lasers, cool lasers, and extract evaporated fountain solution during DALI printing operations.
VCSEL Array Chip Designs
In an example implementation for printing, many laser array chips 100 would be arranged side by side along a cross-process (or x) direction for a document 101, as indicated by arrow 103 to form a wide imager 140.
In order to accommodate a large aperture size capable of delivering light outputs of up to 50 mW per laser, an asymmetric laser aperture design can be utilized, instead of a usual circular aperture. The shape of the aperture can be “squeezed” along the direction of the array, so it fits within the available space of the tight pitch arrangement. The aperture can be commensurately “elongated” in the direction of the address line to compensate for the squeezed dimension, so a sufficiently large light-emitting area still can be attained.
The multi-row interdigitated arrangement of pixels in
Mounting, Cooling, Driving, and Imaging VCSEL Array Chips
The tight spacing between lasers in such arrays makes thermal crosstalk problematic, as heat from each laser affects the performance of nearby lasers. Also, the aggregate electrical power draw from a large number of high power lasers operating within a small region leads to a high thermal load density that must be dissipated. Otherwise, the increased temperature will reduce the light output power and can damage the lasers.
These severe thermal management issues can be addressed by developing a direct die attached packaging approach, where the laser array chip is directly die-attached onto a 3D mechanical block, instead of a conventional planar submount. The mechanical block can incorporate embedded cooling fluid channels for flowing cooling fluids such as chilled water or ethylene glycol and functions as a cathode electrical contact for the laser chip. The block can be thought of as a 3D submount with a built-in heat sink. Our 3D submount also features integrated slots for driver chips or electrical interposers and mounting holes for optics mounts. Alternatively, the submount could comprise a heat pipe.
The light output from surface-emitting lasers diverges, so focusing optics are typically needed to structure the light beams and form images. Some commercial GRIN lens array marketed under the name SELFOC lens arrays (SLA) can be configured and used for this purpose. SLAs are well suited for this application because the optical elements can be arranged into a linear arrangement for imaging a set of laser elements that are also arranged in a linear array, such as the ones in applications presented herein. A “base cell” of lenses can be placed into a linear array for this purpose.
SLAs are devices that can be used to project a 1:1 image from a source to a substrate. These devices are typically quasi 1-dimensional and are used in scanning applications such as photocopiers, scanners, printers, and fax machines. Typically, SLAs are commercially available in 2-rows of index graded optical elements bonded together in formats and they can be used in some print applications such as LED print bars. Each optical element collects light from a source and projects it on to a substrate. Images from all the optical elements superimpose in order to form the projection of the source onto the substrate. SLAs are attractive because their size can be relatively large so that they become usable for printing applications which typically require wide print width. Commercial SLAs are approximately 12 inch wide. In accordance with the present embodiments, should significantly wider print widths be required, several SLAs could be stitched along the cross-process direction or longer custom SLAs could be produced, or complete VCSEL print bars could be staggered for use in a wide Dali print process.
A larger number of lens rows can be constructed from commercially available 2-row SLAs by removing the cladding from one side of the SLA, polishing away the cladding residues, and pressing two modified SLAs together. Referring to
Alternative Focusing Optics
In many cases the desired print width makes a classical imaging system too large. Instead of using SLAs to focus an image 110 of individual VCSEL lasers of a laser array 100 on a blanket cylinder 266, it also can be possible to use different optical elements such as classical focusing lenses 263. These types of lenses or lens combinations create inverted images of an object. Referring to
There is an alternative interposer design that can fan the contact pitch in, rather than out. In such designs, the VCSEL array pads can be mapped to corresponding tighter-pitch pads, say, on the output of a driver chip (ASIC). The fan-in arrangement allows the driver chip to be made smaller than the laser array chip, thus providing placement tolerance when aligning and tiling driver chips for addressing tiled laser array chips 100 like those in
In certain applications, the ability to directly attach the laser array chip 210 onto a large highly thermally conductive block 220 is essential for preventing thermal overload, because a traditional 2D planar submount would add unacceptable thermal resistance between the laser chip 210 and a heat sink. In the presented cooling design as described with respect to
The semiconductor laser substrate is typically highly thermally resistive compared to a metal block, so the substrate can present a significant bottleneck to thermal flow from heat generated at the lasers. Thermal modeling indicates that thinning the substrate from a conventional 150 μm thick layer to 40 μm can reduce the temperature at the laser by 12° C. during operation, assuming a coolant flow rate of 4 liters per minute. This can translate into a light output power improvement of about 10%. The temperature at the laser can be reduced further with the use of thinner substrates down to a substrate thickness of 20 μm.
A 20 μm-thick layer is in the order of the thickness of the VCSEL epitaxial layers, so the substrate thinning task is tantamount to removing the epi material from its native substrate and transferring it to a host metal substrate.
VCSEL Array Printing Application Example
Not meant as a limitation for application herein disclosed embodiments, as mentioned hereinbefore, the use of VCSEL arrays as an individually addressable light source in, for example, digital architecture for lithographic inks (DALI) printing systems. DALI print processing has the advantage of a dramatically reduced size, cost, and complexity of the most sophisticated component—the laser imager.
The imaging member 266 can be used to apply an ink image to an image receiving media substrate 114 at a transfer nip 112. The transfer nip 112 can be formed by an impression roller 118, as part of an image transfer mechanism 160, exerting pressure in the direction of the imaging member 266. The image receiving media substrate 114 should not be considered to be limited to any particular composition such as, for example, paper, plastic, or composite sheet film. The digital printing system 370 may be used for producing images on a wide variety of image receiving media substrates.
The imaging member 266 can include a reimageable surface layer formed over a structural mounting layer that may be, for example, a cylindrical core, or one or more structural layers over a cylindrical core.
The digital printing system 370 can include a fountain solution system 122 that involves a series of rollers, which may be considered as dampening rollers or a dampening unit, for uniformly wetting the reimageable surface of the imaging member 266 with dampening fluid. A purpose of the fountain solution system 122 is to deliver a layer of dampening fluid, generally having a uniform and controlled thickness, to the reimageable surface of the imaging member 266.
As indicated above, it is known that a dampening fluid such as fountain solution may comprise mainly water optionally with small amounts of isopropyl alcohol or ethanol added to reduce surface tension as well as to lower evaporation energy necessary to support subsequent laser patterning, as will be described in greater detail below. Small amounts of certain surfactants may be added to the fountain solution as well. Alternatively, other suitable dampening fluids may be used to enhance the performance of ink based digital lithography systems.
Once the dampening fluid is metered onto the reimageable surface of the imaging member 266, a thickness of the dampening fluid may be measured using a sensor 125 that may provide feedback to control the metering of the dampening fluid onto the reimageable surface of the imaging member 266 by the fountain solution system 122.
After a precise and uniform amount of dampening fluid is provided by the fountain solution system 122 on the reimageable surface of the imaging member 266, an optical patterning subsystem 130 may be used to selectively form a latent image in the uniform dampening fluid layer by image-wise patterning the dampening fluid layer using, for example, laser energy. Typically, the dampening fluid may not absorb the optical energy (IR or visible) efficiently. The optical patterning subsystem 130 can be implemented as or may include a light source 131 (e.g., a vertical cavity surface emitting (VCSEL) array, a light emitting diode (LED) array, a laser light source that emits the pixilated light beam as a pixelated line laser beam, or a modulated laser line source).
The reimageable surface of the imaging member 266 should ideally absorb most of the laser energy (visible or invisible such as IR) emitted from the optical patterning subsystem 130 close to the surface to minimize energy wasted in heating the dampening fluid and to minimize lateral spreading of heat in order to maintain a high spatial resolution capability. Alternatively, an appropriate radiation sensitive component may be added to the dampening fluid to aid in the absorption of the incident radiant laser energy. While the optical patterning subsystem 130 is described above as being or including a light source such as a laser emitter, it should be understood that a variety of different systems may be used to deliver the optical energy to pattern the dampening fluid.
The mechanics at work in the patterning process undertaken by the optical patterning subsystem 130 are known to those in the art. Briefly, the application of optical patterning energy from the optical patterning subsystem 130 can result in selective removal of portions of the layer of dampening fluid.
Following patterning of the dampening fluid layer by the optical patterning subsystem 130, the patterned layer over the reimageable surface of the imaging member 266 can be presented to an inker subsystem 145. The inker subsystem 145 can be used to apply a uniform layer of ink over the layer of dampening fluid and the reimageable surface layer of the imaging member 266. The inker unit 145 can further include heated ink baths whose temperatures can be regulated by a temperature control module (not shown in
The cohesiveness and viscosity of the ink residing in the reimageable layer of the imaging member 110 can be modified by a number of mechanisms. One such mechanism, for example, can involve the use of a rheology (complex viscoelastic modulus) control subsystem 155. The rheology control system 155 can form a partial crosslinking core of the ink on the reimageable surface to, for example, increase ink cohesive strength relative to the reimageable surface layer. Curing mechanisms may include optical or photo curing, heat curing, drying, or various forms of chemical curing. Cooling may be used to modify rheology as well via multiple physical cooling mechanisms, as well as via chemical cooling.
The ink can be then transferred from the reimageable surface of the imaging member 266 to a substrate of image receiving medium 114 using a transfer subsystem 160. The transfer occurs as the substrate 114 is passed through a nip 112 between the imaging member 266 and an impression roller 118 such that the ink within the voids of the reimageable surface of the imaging member 266 is brought into physical contact with the substrate 114. With the adhesion of the ink having been modified by the rheology control system 155, modified adhesion of the ink causes the ink to adhere to the substrate 114 and to separate from the reimageable surface of the imaging member 266. Careful control of the temperature and pressure conditions at the transfer nip 112 can allow transfer efficiencies for the ink from the reimageable surface of the imaging member 266 to the substrate 114 to exceed 95%. While it is possible that some dampening fluid may also wet substrate 114, the volume of such a dampening fluid will be minimal and will rapidly evaporate or be absorbed by the substrate 114.
In certain offset lithographic systems, it should be recognized that an offset roller (not shown in
Other mechanisms by which cleaning of the reimageable surface of the imaging member 266 can be facilitated. Regardless of the cleaning mechanism, however, cleaning of the residual ink and dampening fluid from the reimageable surface of the imaging member 266 can be essential to preventing so-called ‘ghosting’. Once cleaned, the reimageable surface of the imaging member 266 can be again presented to the fountain solution system 122 by which a fresh layer of dampening fluid can be supplied to the reimageable surface of the imaging member 266, and the process can be repeated.
In the prior art digital printing system 370 shown in
The ink must be compatible with materials that it comes into contact with, including the imaging member 266, fountain solution applied by fountain solution system 122, and other cured or non-cured inks. The ink should also meet all functional requirements of the sub-systems, including wetting and transfer properties. Transfer of the imaged inks is challenging, as the ink must at once wet the blanket material homogeneously (e.g., imaging member 266), and transfer from the blanket 113 to the substrate (112, 114, and 118). Transfer of the image layer must be very efficient, at least as high as 90%, as the cleaning sub-station can only eliminate small amounts of residual ink. Any ink remaining on the blanket after cleaning would result in an unacceptable ghost image appearing in subsequent prints. Not surprisingly, ink rheology plays a key role in the transfer characteristics of an ink.
DALI print systems involve the use of DALI print process high power lasers and the ability to modulate them in a pixel-by-pixel fashion to produce latent fountain solution images that can be used to ink a printing blanket. A DALI system can enable the digital printing of high viscosity inks with high resolution. Such a high quality printing process can combine the inherent advantages of high pigment loading, low solvent content, inexpensive inks with the capability of printing with these inks in a digital fully customizable manner for each pixel in each print.
In the DALI printing process, a continuous thin layer (e.g., tens of nanometers) of fountain solution, which can be deposited on the surface of the printing blanket, rejects the transfer of ink to the blanket 113 (in particular imaging member 266). A high-power laser can be used to heat the surface region of the optically absorbing blanket and thereby evaporate the fountain solution in an image-wise pattern. The laser must, however, heat the blanket sufficiently to supply the latent heat of evaporation as well as the sensible heat to raise the fluid to its evaporation temperature (e.g., —175C). The evaporated areas can be then inked, and the ink can be transferred to a receiving medium.
Although existing DALI printing systems can enable the digital printing of high viscosity inks with a high resolution, the current DALI printing process can be relatively expensive due to the cost of high-power lasers and their modulation devices. Solutions such as those described with respect to the embodiments described herein are thus needed to reduce costs significantly for DALI printing systems.
A design drawing of a completed VCSEL array-based imaging member 380 is depicted in the perspectives presented in
In summary, disclosed here are structures and methods for realizing tight-pitch independently-addressable high power surface-emitting laser arrays. Also described are associated components and methods to enable use of such laser arrays in printing applications.
It will be appreciated that variations of the above-disclosed and other features and functions, or alternatives thereof, may be desirably combined into many other different systems or applications. It will also be appreciated that various presently unforeseen or unanticipated alternatives, modifications, variations, or improvements therein may be subsequently made by those skilled in the art which are also intended to be encompassed by the following claims.
1. A laser imager for a printing system, comprising:
- more than 100 independently addressable lasers arranged in a linear array on a common substrate chip, wherein the independently addressable lasers are vertical cavity surface emitting lasers (VCSELs) including an oblong aperture and more than one aperture per control channel;
- a dedicated control channel associated with an address trace line to support communication from driver electronics with each independently addressable laser of the independently addressable lasers; and
- optical elements configured to capture and focus light from the independently addressable lasers, wherein the optical elements are also arranged in a linear lens array and operate together with the independently addressable lasers to create an image of the independently addressable lasers on an imaging member with an optical intensity greater than 20 W/mm2.
2. The laser imager of claim 1, wherein the independently addressable lasers share a cathode through the substrate of the common substrate chip.
3. The laser imager of claim 1, wherein the optical elements are embodied in a GRIN lens array.
4. The laser imager of claim 1, wherein the common substrate chip is coupled to a mechanical block including at least one cooling fluid channel therein and configured to control temperature of the independently addressable lasers during their operation.
5. The laser imager of claim 1, further comprising a drive electronics chip providing power from the driver electronics to the independently addressable lasers via each dedicated control channel associated with the address trace line for each laser of the independently addressable lasers.
6. The laser imager of claim 5, further comprising more than one common substrate chips tiled and stitched together side-by-side to provide an at least 11-inch wide imager.
7. The laser imager of claim 6, further comprising the more than one common substrate chips tiled and stitched together in a staggered arrangement.
8. The laser imager of claim 6, wherein a linear density of the independently addressable lasers is greater than 10 laser pixels per millimeter.
9. The laser imager of claim 1, further comprising provisions to extract fountain solution.
10. The laser imager of claim 1, wherein the independently addressable lasers emit light in the wavelength range of 550 nm to 1000 nm.
11. The laser imager of claim 1, wherein the optical elements create an un-inverted image of the independently addressable lasers in the laser array.
12. The laser imager of claim 1, wherein each address trace line associated with each control channel for each of the plurality of independently addressable lasers further comprises more than one aperture operable in common to attain a larger effective aperture size.
13. The laser imager of claim 12, wherein the more than one aperture operable in common to attain the larger effective aperture size is a double-aperture pixel.
14. A laser imager for a printing system, comprising:
- more than one hundred independently addressable lasers arranged in a linear array on a common substrate chip, wherein the independently addressable lasers are vertical cavity surface emitting lasers including an oblong aperture and more than one aperture per control channel;
- driver electronics embodied in an application specific integrated circuit (ASIC);
- a dedicated control channel associated with an address trace line to support communication from the driver electronics with each independently addressable laser of the independently addressable lasers; and
- optical elements arranged in a linear lens array and configured to capture and focus light, forming an image of the independently addressable lasers onto an imaging member at an optical intensity larger than 20 W/mm2.
15. The laser imager of claim 14, wherein the independently addressable lasers are tiled together side-by-side on the common substrate to provide an at least 11-inch wide stitched imaging on to the imaging member at least 300 dots per inch.
16. The laser imager of claim 15, wherein the common substrate chip is coupled to a mechanical block including at least one cooling fluid channel therein and configured control temperature of the independently addressable lasers during their operation.
17. A laser imaging method, comprising:
- providing lasers comprising more than 100 independently addressable lasers tiled together in a linear laser array on a common substrate chip, a dedicated control channel associated with an address trace line to support communication from driver electronics with each independently addressable laser of the independently addressable lasers, and optical elements configured to capture and focus light from the independently addressable lasers, wherein the independently addressable lasers are vertical cavity surface emitting lasers including an oblong aperture and more than one aperture per control channel and wherein the optical elements are arranged in a linear lens array and operate together with the lasers to create an image from the independently addressable lasers onto an imaging member with an optical intensity larger than 20 W/mm2;
- depositing a fountain solution provided from vapor phase module onto a surface of the imaging member;
- digitally patterning the fountain solution with an image based on electrical current provided by the driver electronics using laser light emitting from the linear laser array, wherein the imaging member becomes heated by the light and the fountain solution selectively evaporates from hot portions of the imaging member and remains on cold portions of the imaging member as a negative image of the image on the imaging member based on a digital pattern lased from the light of the linear array via the optical elements;
- extracting fountain solution vapor via a vacuum source to prevent re-condensation of the fountain solution on the imaging member;
- transferring high viscosity ink from an inking source to the imaging member, wherein the high viscosity ink forms on the imaging member and is rejected, wherein fountain solution remains on the imaging member; and
- transferring the high viscosity ink from the imaging member to a substrate leaving an 1:1 copy of the image on the substrate.
18. The method of claim 17, wherein more than one common substrate chips bearing surface emitting lasers among the independently addressable lasers are tiled together side-by-side to provide an at least 11-inch wide imager.
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Filed: Aug 23, 2021
Date of Patent: Nov 28, 2023
Patent Publication Number: 20230055149
Assignee: Xerox Corporation (Norwalk, CT)
Inventors: Joerg Martini (San Francisco, CA), Christopher Chua (San Jose, CA), Zhihong Yang (San Jose, CA), Mark Teepe (Palo Alto, CA), Patrick Y. Maeda (Mountain View, CA), Sourobh Raychaudhuri (Palo Alto, CA), Elif Karatay (Palo Alto, CA), Noble M. Johnson (Menlo Park, CA), David K. Biegelsen (Portola Valley, CA), Joseph Lee (Palo Alto, CA)
Primary Examiner: Justin Seo
Assistant Examiner: Kendrick X Liu
Application Number: 17/408,814
International Classification: H01S 5/042 (20060101); H01S 5/40 (20060101); H01S 5/42 (20060101); H01S 5/183 (20060101); B41J 2/44 (20060101); B41J 2/45 (20060101); B41J 2/455 (20060101); B41J 2/47 (20060101); G02B 19/00 (20060101);